Drill pipe connector

ABSTRACT

An assembly is disclosed for adapting a peripheral-return bit to a reverse circulation double-walled drill-pipe. Two cylindrical coaxial members are rigidly mounted together and are adapted to be attached at one end to the outer and inner pipes of the drillpipe. At the other end is a bit holder. The return from a peripheral-return bit in the holder passes into the centre of the inside cylindrical member through radial slots traversing both cylindrical coaxial members, while the pressurized air from the annular space between the two pipes of the drill-pipe enters the bit through radial passages which open into the bit-supporting bore of the bit-holder.

United States Patent 1 Becker 14s] Jan. 14', 1975 1 DRILL PIPE CONNECTOR Floyd Walter Becker, Calgary, Alberta, Canada [73] Assignee: Becker Drills Ltd., Calgary, Alberta,

' Canada 22 Filed: May 2,1973

21 Appl. No.: 356,703

[75] inventor:

[52] US. Cl 285/133 A [51] Int. Cl. F16] 47/00 [58] Field of Search 285/133 A [56] References Cited UNITED STATESPATENTS 3,065,807 11/1962 Wells 285/133 A 3,193,308 7/1965 Todd 285/133 A 3,786,878

1/1974 Chapman 285/133 A Primary Examiner-Patrick D. Lawson Attorney, Agent, or Firm-James A. Lamb [57] ABSTRACT An assembly is disclosed for adapting a peripheralreturn bit to a reverse circulation double-walled drillpipe. Two cylindrical coaxialmembers are rigidly mounted together and are adapted to be attached at.

one end to the outer and inner pipes of the drill-pipe. At the other end is a bit holder. The return from a peripheral-return bit in the holder passes into the centre of the inside cylindrical member through radial slots traversing both cylindrical coaxial members, while the pressurized air from tl1 e annular space between the two bifls of the drill-pipe enters the bit through radial passages which open into the bitsupporting bore of the bit-holder.

7 Claims, 4 Drawing Figures I PATENTEUJANMISIS 3.860.272

SHEET 10F 2 FIGJ PATENTED JAN 1 M975 SHEET 2 OF 2 mm Vm @m OF mm Vm OW NP DRILL PIPE CONNECTOR BACKGROUND OF THE INVENTION This invention relates generally to the art of drilling bore holes in the earth, and relates particularly to a drill-pipe accessory for adapting a particular kind of drill bit to a drill-pipe construction with which it is ordinarily not compatible.

One conventional drill-pipe construction is known as double-walled drill-pipe, which is especially designed for reverse circulation flow. Reverse circulation drilling with double-walled drill-pipe requires circulation down the outer annulus of the drill-pipe and up along the centre core. The drilling fluid, commonly air, is discharged from the bottom of the annulus around the periphery of the drill bit, where it picks up the cuttings from the formation and carries them to the centre of the drill bit, at which point the fluid and the cuttings can enter the centre of the double-walled drill-pipe and return along this centre core to the surface, for sampling. This method is a very accurate and economical way of obtaining contamination-free samples of the drilled formation, and is widely used by the mining industry for exploration purposes.

The wide range of formation hardness in the earths strata and the need for economy in drilling has led recently to the development of many drill-bit designs, and to the introduction of down-the-hole percussion tools. Some of these drill-bits, and particularly the percussion tools, require a drilling fluid circulation pattern which is opposite to that normally occurring in a reverse circulation double-walled drill-pipe. In other words, with these particular drill-bits, the fluid is forced down the centre of the drill-pipe, out the centre of the drill bit, across the bit face to pick up the cuttings, and up along the annulus between the drilled hole and the drill-pipe. Ordinarily, double-walled drill-pipe is not used with these bits. In the case of a percussion tool, the greater part of the fluid is forced through the tool to provide power to operate the tool, and is then ejected through relatively small holes at the centre of the bit.

It will be appreciated that, when this sort of bit is used for sampling purposes, there is a serious risk that the cuttings will be contaminated by cavings from the walls of the hole or from the washing effect of the fluid along the walls of the hole.

In order to be able to use these special drill-bits (those in which the fluid flow is downwardly through the centre and outwardly across the face) for sampling, it would be of advantage to use them with doublewalled drill-pipe, in which the risk of contamination is eliminated. The problem is of course conveying the fluid from the annulus of the double-walled drill-pipe to the centre of the bit, and then from the periphery of the bit back to the centre core of the double-walled drill-pipe.

SUMMARY OF THE INVENTION In view of the foregoing disadvantages of the prior art, it is one object of this invention to provide a drillpipe accessory capable of adapting a centre-feed peripheral-return drill-bit to a double-walled drill-pipe suited to reverse circulation.

The general approach of this invention is to provide an assembly which includes a bit holder having an internally threaded bit-supporting passage, outer and inner cylindrical members coaxial with one another with the outer cylindrical member partially overlapping the bit holder, and one or more sealed passageways from the bit-supporting passage into-the annular space between the two cylindrical members. At least one aperture is provided which communicates the interior of the inner cylindrical member with the periphery of the bit holder, and the aperture is sealed against communication with the annular space between the outer and the inner cylindrical members. Means are also provided for attaching the outer and inner cylindrical members to the bottom of the outer and inner pipes of a doublewalled drill-pipe.

BRIEF DESCRIPTION OF DRAWINGS One embodiment of this invention is shown in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which:

FIG. 1 is a partly broken-away perspective view of the adapter accessory of this invention;

FIG. 2 is an axial sectional view of a portion of the device shown in FIG. 1;

FIG. 3 is a cross-sectional view taken at the line 3--3 in FIG. 1; and

FIG. 4 'is a plan view of the portion of the device shown in FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENTS Attention is first directed to FIG. 1, in which is shown an assembly for adapting a peripheral-return bit to a reverse-circulation double-walled drill-pipe which includes an outer pipe and an inner pipe concentric with the outer pipe.

The assembly, denoted generally by the numeral 10 is seen to include a bit holder 12 which has an internally threaded bit-supporting passage 14 which is conical in shape, as in conventional bit holders. The bitsupporting passage 14 has a cylindrical coaxial extension 15 (see FIG. 2). The bit holder 12 is generally of cylindrical configuration. The assembly 10 further includes an outer cylindrical member 16, and a coaxial inner cylindrical member 18. The inner cylindrical member 18 is coaxial with the bit holder 12, and is welded thereto at 19, as shown in FIG. 2. The bit holder 12 has a reduced cylindrical extension 20 which snugly fits within the inner cylindrical member 18, and closes the same. As can be seen particularly in FIGS. 1 and 2, the outer cylindrical member 16 partially overlaps the bit holder 12. Preferably, the outer cylindrical member 16 terminates approximately mid-way axially of the bit holder 12.

Four radial passageways 22 (two visible in each of FIGS. 1, 2 and 4) are provided in the bit holder 12 to communicate the cylindrical extension 15 of the bitsupporting passage 14 with the annular space 24 which is defined between the outer cylindrical member 16 and the inner cylindrical member 18. It is thus appreciated that fluid forced down between the outer cylindrical member 16 and the inner cylindrical member 18 can pass into the bit-supporting passage 14 through the passageways 22.

In FIG. 2 a peripheral-return bit 25 is shown in broken lines, and has a centre passageway 26 through which the fluid passes downwardly (leftwardly in FIG. 2). The fluid then moves radially outwardly across the face 28 of the peripheral-return bit 25, and returns, as shown by the arrows, upwardly along the periphery of the peripheral-return bit 25.

The problem of how to pass the upwardly returning fluid into the interior of the inner cylindrical member 18 is solved, as shown in FIG. 1, by the provision of scaled slots 30. More specifically, the inner cylindrical member 18 has two antipodal longitudinal slots 32 extending from its leftward end for a certain distance along its length, and the outer cylindrical member 16 has two antipodal longitudinal slots 34 in radial registry with the slots 32. A wall strip 36 runs along the edges of the slots between the outer and inner cylindrical members, and is sealed to both. As seen in FIG. 2, a sealing plate 38 is provided at the upper ends of the slots 30, while blocks 40 are provided at the lower end of the outer cylindrical member 16 between the slots 30. The provision of these means 36, 38 and 40 effectively seals the annular space 24 between the outer cylindrical member 16 and the inner cylindrical member 18 from any communication with either the slots 30 or the interior of the inner cylindrical member 18.

It is thus seen that the fluid returning up along the periphery of the peripheral-return bit 25 can return to the interior of the inner cylindrical member 18 through the slots 30, without interfering in any way with the downward passage of fluid through the annular space 24 between the outer and inner cylindrical members 16 and 18.

The Figures show appropriate welding beads between the cylindrical members (including the bit holder 12) and the means 36, 38 and 40.

It will be noted that the upper ends of the slots 30 diverge outwardly toward the bit holder 12.

In FIG. 1 is shown the provision of two stiffening members 43 running longitudinally of the assembly and extending radially between the outer cylindrical member 16 and both the bit holder 12 and the inner cylindrical member 18. The stiffening members 43 are at antipodal locations equidistant from the two slots 30 in the assembly.

As can be seen in FIG. 1, the outer cylindrical member 16 has, at its upper end (rightward end in FIG. 1) an internally threaded attachment collar 45 adapted to connect the assembly 10 to the outer pipe 46 of a conventional double-walled drill-pipe adapted for reverse circulation drilling. As can also be seen in FIG. 1, the internal pipe 48 of the double-walled drill-pipe is adapted to be pressure sealed at 49 to the upper end of the inner cylindrical member 18 of the assembly 10.

I claim:

1. An assembly for adapting a peripheral-return bit to a reverse circulation double-walled drill-pipe which includes an outer pipe and an inner pipe concentric with said outer pipe, said assembly comprising:

a bit holder having a wall defining an internally threaded bit-supportin g passage,

an outer and an inner cylindrical member coaxial with one another, the outer cylindrical member partially overlapping said bit holder,

means defining a sealed passageway extending through the wall of said bit holder from said bitsupporting passage into the annular space between said cylindrical members,

and means extending through said inner and outer cylindrical members defining at least one aperture communicating the interior of the inner cylindrical member with the periphery of the bit holder, said at least one aperture being sealed against communication with said annular space,

the outer and inner cylindrical members, at their ends remote from the bit holder, being adapted to sealed attachment to, respectively, said outer and inner pipes.

2. An assembly for adapting a peripheral-return bit to a reverse circulation double-walled drill-pipe which includes an outer pipe and an inner pipe concentric with said outer pipe, said assembly comprising:

an inner cylindrical member having one end closed, a bit holder extending coaxially from said one end, said inner cylindrical member being adapted for connection at its other end to said inner pipe of the double-walled drill-pipe, the inner cylindrical member having aperture means communicating its interior with its exterior between its two ends,

and an outer cylindrical member concentric with said inner cylindrical member and having at one end connector means for attachment to said outer pipe of the double-walled drill-pipe, the outer cylindrical member having longitudinal slot means extending from its other end toward but short of the said one end, said slot means being aligned with said aperture means of the inner cylindrical member, the outer cylindrical member extending around said slot means to partly enclose said bit holder in spaced relation therewith,

radial wall means bordering said slot means and at said other end of the outer cylindrical member, said radial wall means extending between said outer cylindrical member and both the bit holder and said inner cylindrical member, thereby to define a closed passage extending from the annular space between the pipes of said double-walled drill-' pipe to a location exteriorly adjacent said bit holder, the bit holder having an internally threaded bitsupporting passage, and port means communicating said location with said bit-supporting passage.

3. The invention claimed in claim 2, in which said one end of the inner cylindrical member is sealingly connected to the bit holder, which latter closes said one end.

4. The invention claimed in claim 2, in which said slot means includes two antipodal longitudinal slots in said outer cylindrical member, and in which said aperture means includes two antipodal longitudinal slots in said inner cylindrical member.

5. The invention claimed in claim 4, further compris ing two stiffening members running longitudinally of the assembly and extending radially between the outer cylindrical member and both the bit holder and the inner cylindrical member, said stiffening members being at antipodal locations equidistant from said two slots in the inner cylindrical member.

6. The invention claimed in claim 4, in which the portions of the radial wall means which border the ends of the antipodal slots remote from the bit holder diverge outwardly toward the bit holder.

7. An assembly for adapting a peripheral-return bit to a reverse circulation double-walled drill-pipe which includes an outer pipe and an inner pipe concentric with said outer pipe, said assembly comprising an inner cylindrical member defining an interior passage and having a first and a second end, said inner cylindrical member being adapted at its first end for connection to said inner pipe of said doublewalled drill pipe,

a bit holder secured to and extending coaxially from an outer cylindrical member concentric with and spaced from said inner cylindrical member and having a first and a second end, said outer cylindrical member being adapted at its first end for connection to said outer pipe of said double-walled drill pipe, said second end of said outer cylindrical member extending around and spaced from said bit holder for a portion of the length of said bit holder,

longitudinal slot means in said second end of said outer cylindrical member extending part way towards said first end to overlie a portion of said inner cylindrical member,

aperture means in said inner cylindrical wall member in alignment with said overlying slot means in said outer cylindrical member, radial wall means bordering said slot means and extending between said outer cylindrical wall member and both the bit holder and the inner cylindrical member, and closure means at the end of said slot means closest to said first end of said outer cylindrical member extending radially between said outer and said inner cylindrical members and extending laterally between adjacent radial wall means, said aperture means, said slot means, said radial wall means and said closure means defining opening means to said interior passage,

means joining the terminating portion of said second end of said outer cylindrical member to said bit holder,

port means in said bit holder beneath said outer cylindrical member providing a passageway between said internal passage in said bit holder and the space between said inner and outer cylindrical 

1. An assembly for adapting a peripheral-return bit to a reverse circulation double-walled drill-pipe which includes an outer pipe and an inner pipe concentric with said outer pipe, said assembly comprising: a bit holder having a wall defining an internally threaded bitsupporting passage, an outer and an inner cylindrical member coaxial with one another, the outer cylindrical member partially overlapping said bit holder, means defining a sealed passageway extending through the wall of said bit holder from said bit-supporting passage into the annular space between said cylindrical members, and means extending through said inner and outer cylindrical members defining at least one aperture communicating the interior of the inner cylindrical member with the periphery of the bit holder, said at least one aperture being sealed against communication with said annular space, the outer and inner cylindrical members, at their ends remote from the bit holder, being adapted to sealed attachment to, respectively, said outer and inner pipes.
 2. An assembly for adapting a peripheral-return bit to a reverse circulation double-walled drill-pipe which includes an outer pipe and an inner pipe concentric with said outer pipe, said assembly comprising: an inner cylindrical member having one end closed, a bit holder extending coaxially from said one end, said inner cylindrical member being adapted for connection at its other end to said inner pipe of the double-walled drill-pipe, the inner cylindrical member having aperture means communicating its interior with its exterior between its two ends, and an outer cylindrical member concentric with said inner cylindrical member and having at one end connector means for attachment to said outer pipe of the double-walled drill-pipe, the outer cylindrical member having longitudinal slot means extending from its other end toward but short of the said one end, said slot means being aligned with said aperture means of the inner cylindrical member, the outer cylindrical member extending around said slot means to partly enclose said bit holder in spaced relation therewith, radial wall means bordering said slot means and at said other end of the outer cylindrical member, said radial wall means extending between said outer cylindrical member and both the bit holder and said inner cylindrical member, thereby to define a closed passage extending from the annular space between the pipes of said double-walled drill-pipe to a location exteriorly adjacent said bit holder, the bit holder having an internally threaded bit-supporting passage, and port means communicating said location with said bit-supporting passage.
 3. The invention claimed in claim 2, in which said one end of the inner cylindrical member is sealingly connected to the bit holder, which latter closes said one end.
 4. The invention claimed in claim 2, in which said slot means includes two antipodal longitudinal slots in said outer cylindrical member, and in which said aperture means includes two antipodal longitudinal slots in said inner cylindrical member.
 5. The invention claimed in claim 4, further comprising two stiffening members running longitudinally of the assembly and extending radially between the outer cylindrical member and both the bit holder and the inner cylindrical member, said stiffening members being at antipodal locations equidistant from said two slots in the inner cylindrical member.
 6. The invention claimed in claim 4, in which the portions of the radial wall means which border the ends of the antipodal slots remote from the bit holder diverge outwardly toward the bit holder.
 7. An assembly for adapting a peripheral-return bit to a reverse circulation double-walled drill-pipe which includes an outer pipe and an inner pipe concentric with said outer pipe, said assembly comprising an inner cylindrical member defining an interior passage and having a first and a second end, said inner cylindrical member being adapted at its first end for connection to said inner pipe of said double-walled drill pipe, a bit holder secured to and extending coaxially from said second end of said inner cylindrical member, said bit holder having an internal passage with an internal bit mounting thread at the end thereof remote from said inner cylindrical member, the bit holder terminating said interior passage of said inner cylindrical member at said second end of said inner cylindrical member, an outer cylindrical member concentric with and spaced from said inner cylindrical member and having a first and a second end, said outer cylindrical member being adapted at its first end for connection to said outer pipe of said double-walled drill pipe, said second end of said outer cylindrical member extending around and spaced from said bit holder for a portion of the length of said bit holder, longitudinal slot means in said second end of said outer cylindrical member extending part way towards said first end to overlie a portion of said inner cylindrical member, aperture means in said inner cylindrical wall member in alignment with said overlying slot means in said outer cylindrical member, radial wall means bordering said slot means and extending between said outer cylindrical wall member and both the bit holder and the inner cylindrical member, and closure means at the end of said slot means closest to said first end of said outer cylindrical member extending radially between said outer and said inner cylindrical members and extending laterally between adjacent radial wall means, said aperture means, said slot means, said radial wall means and said closure means defining opening means to said interior passage, means joining the terminating portion of said second end of said outer cylindrical member to said bit holder, port means in said bit holder beneath said outer cylindrical member providing a pasSageway between said internal passage in said bit holder and the space between said inner and outer cylindrical members. 